/Engine/Source/Runtime/GeometryCore/Public/Spatial/ZOrderCurvePoints.h
Generate a "z-order curve" ordering for a point set by distributing the points to a quad- or octree and then reading the points indices back in tree traversal order This is useful for giving the points spatial locality  so points that are close together in the ordering tend to be close together spatially, also
struct FZOrderCurvePoints
int32
MaxTreeDepth
Inputs.
TArray< int32 >
Order
Outputs.